Is there a unified description of conductivity of layered cuprates?

We present a novel approach to the analysis of the normal state in-plane si gma(ab) and out-of-plane sigma(c) conductivities of anisotropic layered cry stals such as oxygen deficient YBa2Cu3Ox. It can be shown that the resistiv e anisotropy is determined by the ratio of the phase coherence lengths in t he respective directions; i.e., sigma(ab)/sigma(c) = l(ab)(2)/l(c)(2). From the idea that at all doping levels and temperatures T the out-of-plane tra nsport in these crystals is incoherent: follows that l(c) is T-independent, equal to the spacing l(0) between the neighboring bilayers. Thus, the T-de pendence of l(ab) is given by the measured anisotropy, and sigma(ab)(l(ab)) dependence is obtained by plotting sigma(ab) vs l = (sigma(ab)/sigma(c))(1 /2)l(0). The analysis of several single crystals of YBa2Cu3Ox (6.35 < x < 6 .93) shows that for all of them sigma(ab)(l) is described by a universal de pendence sigma(ab)/<(sigma)over bar> = f(l/(l) over bar) with doping depend ent parameters <(sigma)over bar> and (l) over bar.